package controller

import (
	"crypto/rand"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"time"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	flaggerv1 "github.com/stefanprodan/flagger/pkg/apis/flagger/v1alpha3"
	clientset "github.com/stefanprodan/flagger/pkg/client/clientset/versioned"
	"go.uber.org/zap"
	appsv1 "k8s.io/api/apps/v1"
	hpav1 "k8s.io/api/autoscaling/v2beta1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/client-go/kubernetes"
)

// CanaryDeployer is managing the operations for Kubernetes deployment kind
type CanaryDeployer struct {
	kubeClient    kubernetes.Interface
	flaggerClient clientset.Interface
	logger        *zap.SugaredLogger
	configTracker ConfigTracker
}

// Promote copies the pod spec, secrets and config maps from canary to primary
func (c *CanaryDeployer) Promote(cd *flaggerv1.Canary) error {
	targetName := cd.Spec.TargetRef.Name
	primaryName := fmt.Sprintf("%s-primary", targetName)

	canary, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(targetName, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return fmt.Errorf("deployment %s.%s not found", targetName, cd.Namespace)
		}
		return fmt.Errorf("deployment %s.%s query error %v", targetName, cd.Namespace, err)
	}

	primary, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(primaryName, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return fmt.Errorf("deployment %s.%s not found", primaryName, cd.Namespace)
		}
		return fmt.Errorf("deployment %s.%s query error %v", primaryName, cd.Namespace, err)
	}

	// promote secrets and config maps
	configRefs, err := c.configTracker.GetTargetConfigs(cd)
	if err != nil {
		return err
	}
	if err := c.configTracker.CreatePrimaryConfigs(cd, configRefs); err != nil {
		return err
	}

	primaryCopy := primary.DeepCopy()
	primaryCopy.Spec.ProgressDeadlineSeconds = canary.Spec.ProgressDeadlineSeconds
	primaryCopy.Spec.MinReadySeconds = canary.Spec.MinReadySeconds
	primaryCopy.Spec.RevisionHistoryLimit = canary.Spec.RevisionHistoryLimit
	primaryCopy.Spec.Strategy = canary.Spec.Strategy

	// update spec with primary secrets and config maps
	primaryCopy.Spec.Template.Spec = c.configTracker.ApplyPrimaryConfigs(canary.Spec.Template.Spec, configRefs)

	// update pod annotations to ensure a rolling update
	annotations, err := c.makeAnnotations(canary.Spec.Template.Annotations)
	if err != nil {
		return err
	}
	primaryCopy.Spec.Template.Annotations = annotations

	_, err = c.kubeClient.AppsV1().Deployments(cd.Namespace).Update(primaryCopy)
	if err != nil {
		return fmt.Errorf("updating deployment %s.%s template spec failed: %v",
			primaryCopy.GetName(), primaryCopy.Namespace, err)
	}

	return nil
}

// IsPrimaryReady checks the primary deployment status and returns an error if
// the deployment is in the middle of a rolling update or if the pods are unhealthy
// it will return a non retriable error if the rolling update is stuck
func (c *CanaryDeployer) IsPrimaryReady(cd *flaggerv1.Canary) (bool, error) {
	primaryName := fmt.Sprintf("%s-primary", cd.Spec.TargetRef.Name)
	primary, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(primaryName, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return true, fmt.Errorf("deployment %s.%s not found", primaryName, cd.Namespace)
		}
		return true, fmt.Errorf("deployment %s.%s query error %v", primaryName, cd.Namespace, err)
	}

	retriable, err := c.isDeploymentReady(primary, cd.GetProgressDeadlineSeconds())
	if err != nil {
		return retriable, fmt.Errorf("Halt advancement %s.%s %s", primaryName, cd.Namespace, err.Error())
	}

	if primary.Spec.Replicas == int32p(0) {
		return true, fmt.Errorf("Halt %s.%s advancement primary deployment is scaled to zero",
			cd.Name, cd.Namespace)
	}
	return true, nil
}

// IsCanaryReady checks the primary deployment status and returns an error if
// the deployment is in the middle of a rolling update or if the pods are unhealthy
// it will return a non retriable error if the rolling update is stuck
func (c *CanaryDeployer) IsCanaryReady(cd *flaggerv1.Canary) (bool, error) {
	targetName := cd.Spec.TargetRef.Name
	canary, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(targetName, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return true, fmt.Errorf("deployment %s.%s not found", targetName, cd.Namespace)
		}
		return true, fmt.Errorf("deployment %s.%s query error %v", targetName, cd.Namespace, err)
	}

	retriable, err := c.isDeploymentReady(canary, cd.GetProgressDeadlineSeconds())
	if err != nil {
		if retriable {
			return retriable, fmt.Errorf("Halt advancement %s.%s %s", targetName, cd.Namespace, err.Error())
		} else {
			return retriable, fmt.Errorf("deployment does not have minimum availability for more than %vs",
				cd.GetProgressDeadlineSeconds())
		}
	}

	return true, nil
}

// IsNewSpec returns true if the canary deployment pod spec has changed
func (c *CanaryDeployer) IsNewSpec(cd *flaggerv1.Canary) (bool, error) {
	targetName := cd.Spec.TargetRef.Name
	canary, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(targetName, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return false, fmt.Errorf("deployment %s.%s not found", targetName, cd.Namespace)
		}
		return false, fmt.Errorf("deployment %s.%s query error %v", targetName, cd.Namespace, err)
	}

	if cd.Status.LastAppliedSpec == "" {
		return true, nil
	}

	newSpec := &canary.Spec.Template.Spec
	oldSpecJson, err := base64.StdEncoding.DecodeString(cd.Status.LastAppliedSpec)
	if err != nil {
		return false, fmt.Errorf("%s.%s decode error %v", cd.Name, cd.Namespace, err)
	}
	oldSpec := &corev1.PodSpec{}
	err = json.Unmarshal(oldSpecJson, oldSpec)
	if err != nil {
		return false, fmt.Errorf("%s.%s unmarshal error %v", cd.Name, cd.Namespace, err)
	}

	if diff := cmp.Diff(*newSpec, *oldSpec, cmpopts.IgnoreUnexported(resource.Quantity{})); diff != "" {
		//fmt.Println(diff)
		return true, nil
	}

	return false, nil
}

// ShouldAdvance determines if the canary analysis can proceed
func (c *CanaryDeployer) ShouldAdvance(cd *flaggerv1.Canary) (bool, error) {
	if cd.Status.LastAppliedSpec == "" || cd.Status.Phase == flaggerv1.CanaryProgressing {
		return true, nil
	}

	newDep, err := c.IsNewSpec(cd)
	if err != nil {
		return false, err
	}
	if newDep {
		return newDep, nil
	}

	newCfg, err := c.configTracker.HasConfigChanged(cd)
	if err != nil {
		return false, err
	}

	return newCfg, nil

}

// SetStatusFailedChecks updates the canary failed checks counter
func (c *CanaryDeployer) SetStatusFailedChecks(cd *flaggerv1.Canary, val int) error {
	cdCopy := cd.DeepCopy()
	cdCopy.Status.FailedChecks = val
	cdCopy.Status.LastTransitionTime = metav1.Now()

	cd, err := c.flaggerClient.FlaggerV1alpha3().Canaries(cd.Namespace).UpdateStatus(cdCopy)
	if err != nil {
		return fmt.Errorf("canary %s.%s status update error %v", cdCopy.Name, cdCopy.Namespace, err)
	}
	return nil
}

// SetStatusWeight updates the canary status weight value
func (c *CanaryDeployer) SetStatusWeight(cd *flaggerv1.Canary, val int) error {
	cdCopy := cd.DeepCopy()
	cdCopy.Status.CanaryWeight = val
	cdCopy.Status.LastTransitionTime = metav1.Now()

	cd, err := c.flaggerClient.FlaggerV1alpha3().Canaries(cd.Namespace).UpdateStatus(cdCopy)
	if err != nil {
		return fmt.Errorf("canary %s.%s status update error %v", cdCopy.Name, cdCopy.Namespace, err)
	}
	return nil
}

// SetStatusPhase updates the canary status phase
func (c *CanaryDeployer) SetStatusPhase(cd *flaggerv1.Canary, phase flaggerv1.CanaryPhase) error {
	cdCopy := cd.DeepCopy()
	cdCopy.Status.Phase = phase
	cdCopy.Status.LastTransitionTime = metav1.Now()

	if phase != flaggerv1.CanaryProgressing {
		cdCopy.Status.CanaryWeight = 0
	}

	cd, err := c.flaggerClient.FlaggerV1alpha3().Canaries(cd.Namespace).UpdateStatus(cdCopy)
	if err != nil {
		return fmt.Errorf("canary %s.%s status update error %v", cdCopy.Name, cdCopy.Namespace, err)
	}
	return nil
}

// SyncStatus encodes the canary pod spec and updates the canary status
func (c *CanaryDeployer) SyncStatus(cd *flaggerv1.Canary, status flaggerv1.CanaryStatus) error {
	dep, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(cd.Spec.TargetRef.Name, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return fmt.Errorf("deployment %s.%s not found", cd.Spec.TargetRef.Name, cd.Namespace)
		}
		return fmt.Errorf("deployment %s.%s query error %v", cd.Spec.TargetRef.Name, cd.Namespace, err)
	}

	specJson, err := json.Marshal(dep.Spec.Template.Spec)
	if err != nil {
		return fmt.Errorf("deployment %s.%s marshal error %v", cd.Spec.TargetRef.Name, cd.Namespace, err)
	}

	configs, err := c.configTracker.GetConfigRefs(cd)
	if err != nil {
		return fmt.Errorf("configs query error %v", err)
	}

	cdCopy := cd.DeepCopy()
	cdCopy.Status.Phase = status.Phase
	cdCopy.Status.CanaryWeight = status.CanaryWeight
	cdCopy.Status.FailedChecks = status.FailedChecks
	cdCopy.Status.LastAppliedSpec = base64.StdEncoding.EncodeToString(specJson)
	cdCopy.Status.LastTransitionTime = metav1.Now()
	cdCopy.Status.TrackedConfigs = configs

	cd, err = c.flaggerClient.FlaggerV1alpha3().Canaries(cd.Namespace).UpdateStatus(cdCopy)
	if err != nil {
		return fmt.Errorf("canary %s.%s status update error %v", cdCopy.Name, cdCopy.Namespace, err)
	}
	return nil
}

// Scale sets the canary deployment replicas
func (c *CanaryDeployer) Scale(cd *flaggerv1.Canary, replicas int32) error {
	targetName := cd.Spec.TargetRef.Name
	dep, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(targetName, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return fmt.Errorf("deployment %s.%s not found", targetName, cd.Namespace)
		}
		return fmt.Errorf("deployment %s.%s query error %v", targetName, cd.Namespace, err)
	}

	depCopy := dep.DeepCopy()
	depCopy.Spec.Replicas = int32p(replicas)

	_, err = c.kubeClient.AppsV1().Deployments(dep.Namespace).Update(depCopy)
	if err != nil {
		return fmt.Errorf("scaling %s.%s to %v failed: %v", depCopy.GetName(), depCopy.Namespace, replicas, err)
	}
	return nil
}

// Sync creates the primary deployment and hpa
// and scales to zero the canary deployment
func (c *CanaryDeployer) Sync(cd *flaggerv1.Canary) error {
	primaryName := fmt.Sprintf("%s-primary", cd.Spec.TargetRef.Name)
	if err := c.createPrimaryDeployment(cd); err != nil {
		return fmt.Errorf("creating deployment %s.%s failed: %v", primaryName, cd.Namespace, err)
	}

	if cd.Status.Phase == "" {
		c.logger.With("canary", fmt.Sprintf("%s.%s", cd.Name, cd.Namespace)).Infof("Scaling down %s.%s", cd.Spec.TargetRef.Name, cd.Namespace)
		if err := c.Scale(cd, 0); err != nil {
			return err
		}
	}

	if cd.Spec.AutoscalerRef != nil && cd.Spec.AutoscalerRef.Kind == "HorizontalPodAutoscaler" {
		if err := c.createPrimaryHpa(cd); err != nil {
			return fmt.Errorf("creating hpa %s.%s failed: %v", primaryName, cd.Namespace, err)
		}
	}
	return nil
}

func (c *CanaryDeployer) createPrimaryDeployment(cd *flaggerv1.Canary) error {
	targetName := cd.Spec.TargetRef.Name
	primaryName := fmt.Sprintf("%s-primary", cd.Spec.TargetRef.Name)

	canaryDep, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(targetName, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return fmt.Errorf("deployment %s.%s not found, retrying", targetName, cd.Namespace)
		}
		return err
	}

	if appSel, ok := canaryDep.Spec.Selector.MatchLabels["app"]; !ok || appSel != canaryDep.Name {
		return fmt.Errorf("invalid label selector! Deployment %s.%s spec.selector.matchLabels must contain selector 'app: %s'",
			targetName, cd.Namespace, targetName)
	}

	primaryDep, err := c.kubeClient.AppsV1().Deployments(cd.Namespace).Get(primaryName, metav1.GetOptions{})
	if errors.IsNotFound(err) {
		// create primary secrets and config maps
		configRefs, err := c.configTracker.GetTargetConfigs(cd)
		if err != nil {
			return err
		}
		if err := c.configTracker.CreatePrimaryConfigs(cd, configRefs); err != nil {
			return err
		}
		annotations, err := c.makeAnnotations(canaryDep.Spec.Template.Annotations)
		if err != nil {
			return err
		}

		// create primary deployment
		primaryDep = &appsv1.Deployment{
			ObjectMeta: metav1.ObjectMeta{
				Name:      primaryName,
				Labels:    canaryDep.Labels,
				Namespace: cd.Namespace,
				OwnerReferences: []metav1.OwnerReference{
					*metav1.NewControllerRef(cd, schema.GroupVersionKind{
						Group:   flaggerv1.SchemeGroupVersion.Group,
						Version: flaggerv1.SchemeGroupVersion.Version,
						Kind:    flaggerv1.CanaryKind,
					}),
				},
			},
			Spec: appsv1.DeploymentSpec{
				ProgressDeadlineSeconds: canaryDep.Spec.ProgressDeadlineSeconds,
				MinReadySeconds:         canaryDep.Spec.MinReadySeconds,
				RevisionHistoryLimit:    canaryDep.Spec.RevisionHistoryLimit,
				Replicas:                canaryDep.Spec.Replicas,
				Strategy:                canaryDep.Spec.Strategy,
				Selector: &metav1.LabelSelector{
					MatchLabels: map[string]string{
						"app": primaryName,
					},
				},
				Template: corev1.PodTemplateSpec{
					ObjectMeta: metav1.ObjectMeta{
						Labels:      map[string]string{"app": primaryName},
						Annotations: annotations,
					},
					// update spec with the primary secrets and config maps
					Spec: c.configTracker.ApplyPrimaryConfigs(canaryDep.Spec.Template.Spec, configRefs),
				},
			},
		}

		_, err = c.kubeClient.AppsV1().Deployments(cd.Namespace).Create(primaryDep)
		if err != nil {
			return err
		}

		c.logger.With("canary", fmt.Sprintf("%s.%s", cd.Name, cd.Namespace)).Infof("Deployment %s.%s created", primaryDep.GetName(), cd.Namespace)
	}

	return nil
}

func (c *CanaryDeployer) createPrimaryHpa(cd *flaggerv1.Canary) error {
	primaryName := fmt.Sprintf("%s-primary", cd.Spec.TargetRef.Name)
	hpa, err := c.kubeClient.AutoscalingV2beta1().HorizontalPodAutoscalers(cd.Namespace).Get(cd.Spec.AutoscalerRef.Name, metav1.GetOptions{})
	if err != nil {
		if errors.IsNotFound(err) {
			return fmt.Errorf("HorizontalPodAutoscaler %s.%s not found, retrying",
				cd.Spec.AutoscalerRef.Name, cd.Namespace)
		}
		return err
	}
	primaryHpaName := fmt.Sprintf("%s-primary", cd.Spec.AutoscalerRef.Name)
	primaryHpa, err := c.kubeClient.AutoscalingV2beta1().HorizontalPodAutoscalers(cd.Namespace).Get(primaryHpaName, metav1.GetOptions{})

	if errors.IsNotFound(err) {
		primaryHpa = &hpav1.HorizontalPodAutoscaler{
			ObjectMeta: metav1.ObjectMeta{
				Name:      primaryHpaName,
				Namespace: cd.Namespace,
				Labels:    hpa.Labels,
				OwnerReferences: []metav1.OwnerReference{
					*metav1.NewControllerRef(cd, schema.GroupVersionKind{
						Group:   flaggerv1.SchemeGroupVersion.Group,
						Version: flaggerv1.SchemeGroupVersion.Version,
						Kind:    flaggerv1.CanaryKind,
					}),
				},
			},
			Spec: hpav1.HorizontalPodAutoscalerSpec{
				ScaleTargetRef: hpav1.CrossVersionObjectReference{
					Name:       primaryName,
					Kind:       hpa.Spec.ScaleTargetRef.Kind,
					APIVersion: hpa.Spec.ScaleTargetRef.APIVersion,
				},
				MinReplicas: hpa.Spec.MinReplicas,
				MaxReplicas: hpa.Spec.MaxReplicas,
				Metrics:     hpa.Spec.Metrics,
			},
		}

		_, err = c.kubeClient.AutoscalingV2beta1().HorizontalPodAutoscalers(cd.Namespace).Create(primaryHpa)
		if err != nil {
			return err
		}
		c.logger.With("canary", fmt.Sprintf("%s.%s", cd.Name, cd.Namespace)).Infof("HorizontalPodAutoscaler %s.%s created", primaryHpa.GetName(), cd.Namespace)
	}

	return nil
}

// isDeploymentReady determines if a deployment is ready by checking the status conditions
// if a deployment has exceeded the progress deadline it returns a non retriable error
func (c *CanaryDeployer) isDeploymentReady(deployment *appsv1.Deployment, deadline int) (bool, error) {
	retriable := true
	if deployment.Generation <= deployment.Status.ObservedGeneration {
		progress := c.getDeploymentCondition(deployment.Status, appsv1.DeploymentProgressing)
		if progress != nil {
			// Determine if the deployment is stuck by checking if there is a minimum replicas unavailable condition
			// and if the last update time exceeds the deadline
			available := c.getDeploymentCondition(deployment.Status, appsv1.DeploymentAvailable)
			if available != nil && available.Status == "False" && available.Reason == "MinimumReplicasUnavailable" {
				from := available.LastUpdateTime
				delta := time.Duration(deadline) * time.Second
				retriable = !from.Add(delta).Before(time.Now())
			}
		}

		if progress != nil && progress.Reason == "ProgressDeadlineExceeded" {
			return false, fmt.Errorf("deployment %q exceeded its progress deadline", deployment.GetName())
		} else if deployment.Spec.Replicas != nil && deployment.Status.UpdatedReplicas < *deployment.Spec.Replicas {
			return retriable, fmt.Errorf("waiting for rollout to finish: %d out of %d new replicas have been updated",
				deployment.Status.UpdatedReplicas, *deployment.Spec.Replicas)
		} else if deployment.Status.Replicas > deployment.Status.UpdatedReplicas {
			return retriable, fmt.Errorf("waiting for rollout to finish: %d old replicas are pending termination",
				deployment.Status.Replicas-deployment.Status.UpdatedReplicas)
		} else if deployment.Status.AvailableReplicas < deployment.Status.UpdatedReplicas {
			return retriable, fmt.Errorf("waiting for rollout to finish: %d of %d updated replicas are available",
				deployment.Status.AvailableReplicas, deployment.Status.UpdatedReplicas)
		}

	} else {
		return true, fmt.Errorf("waiting for rollout to finish: observed deployment generation less then desired generation")
	}

	return true, nil
}

func (c *CanaryDeployer) getDeploymentCondition(
	status appsv1.DeploymentStatus,
	conditionType appsv1.DeploymentConditionType,
) *appsv1.DeploymentCondition {
	for i := range status.Conditions {
		c := status.Conditions[i]
		if c.Type == conditionType {
			return &c
		}
	}
	return nil
}

// makeAnnotations appends an unique ID to annotations map
func (c *CanaryDeployer) makeAnnotations(annotations map[string]string) (map[string]string, error) {
	idKey := "flagger-id"
	res := make(map[string]string)
	uuid := make([]byte, 16)
	n, err := io.ReadFull(rand.Reader, uuid)
	if n != len(uuid) || err != nil {
		return res, err
	}
	uuid[8] = uuid[8]&^0xc0 | 0x80
	uuid[6] = uuid[6]&^0xf0 | 0x40
	id := fmt.Sprintf("%x-%x-%x-%x-%x", uuid[0:4], uuid[4:6], uuid[6:8], uuid[8:10], uuid[10:])

	for k, v := range annotations {
		if k != idKey {
			res[k] = v
		}
	}
	res[idKey] = id

	return res, nil
}